Seminar – Francesco Belfiore (ESO)

One cloud is not enough: ISM abundances across scales

The measurement of chemical abundances in galaxies is a cornerstone of modern astrophysics, offering crucial insights into nucleosynthesis, the history of star formation, and the exchange of gas between galaxies and their surrounding environment. Nebular emission lines are therefore one of the key tools for tracing how galaxies form and evolve, but what we measure depends on the physical scales under study. A nearby H II region, the integrated light of a star-forming galaxy, and a distant object observed with JWST can all tell us something different about the same underlying processes.

In this talk, I will explore how our picture of interstellar-medium abundances changes with physical scale, and what we can learn by moving from resolved observations of individual regions to integrated spectra of whole galaxies. I will draw on recent results from integral field spectroscopy surveys of nearby galaxies and from JWST observations of extreme objects in the early Universe, where deep spectroscopy is beginning to reveal substantial variations in density and chemical abundance. I will conclude with challenges—and opportunities—for building a consistent picture of galaxy abundances from the local Universe to the Cosmic Dawn by leveraging the next generation of ESO facilities.